Telemetry and command (T&C) subsystems provide the functional interface between a satellite or other such spacecraft and ground command (or base unit). Telemetry data describing the status, configuration, and health of the spacecraft payload is received, while commands are issued to the subsystem through conventional radio frequency (RF) communication methods.
Satellites and other such systems have, in recent years, become increasingly more complicated. For example, satellites have evolved from simple repeaters of limited capabilities and minimal resource demands to highly-capable and complex multi-mission platforms. This increase in capabilities has been accompanied by a corresponding increase in T&C input/output requirements.
Using traditional approaches to connectivity and processing methods, T&C subsystems have thus become substantially more complex and difficult to use. In a typical “one wire/one function” system, for each discrete telemetry measurement, a dedicated output circuit, point-to-point wire, and input buffer/channel are employed to facilitate sampling and encoding. Similarly, each command or discrete state-change execution requires a dedicated circuit, wire, and input buffer/receiver. This model results in functional simplicity, but a large number of individual wires and circuit subsystems (e.g., thousands of individual wires).
In a “three-wire serialization” system, for low-speed serial telemetry data, a dedicated output circuit, five point-to-point wires, input buffers, and a single channel are employed to facilitate data transfer. For high-speed serial command data, a dedicated output circuit, three point-to-points wires, input buffers, and a single channel are used. This model results in a rigid process, low speed, limited capability, and medium complexity.
In a “digital databus serialization” system, serial data for both telemetry and command data for multiple devices are communicated over a single databus. Such multi-wire databus systems provide high speed, and are flexible, but require a high level of user complexity.
Accordingly, it is desirable to provide simplified telemetry and command interfaces. Other desirable features and characteristics of the various embodiments will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.